平坦效率对于实现光中子反应的单中子、双中子和三中子事件的区分和截面的计算非常关键。介绍了一种用于逆康普顿散射γ源(Shanghai Laser Electron Gamma Source,SLEGS)光中子(γ,n)截面测量的4π平坦效率3He中子探测器阵列的设计与模...平坦效率对于实现光中子反应的单中子、双中子和三中子事件的区分和截面的计算非常关键。介绍了一种用于逆康普顿散射γ源(Shanghai Laser Electron Gamma Source,SLEGS)光中子(γ,n)截面测量的4π平坦效率3He中子探测器阵列的设计与模拟。采用Geant4程序对平坦效率3He探测器的优化布局和效率进行了模拟,针对设计的由20只Φ50 mm×500 mm 5 cm 3He正比计数管和6只Φ25 mm×500 mm 3He正比计数管组成的4π平坦效率中子探测器,模拟给出探测器平均效率曲线在1 keV^6 MeV的效率为34.4%~45.9%。模拟中以209Bi靶为例,靶尺寸为Φ20 mm×4 mm,通过对产生中子的角分布,能谱的模拟计算,发现中子出射角度在90°对称,探测器的4π布局能够完全覆盖入射到聚乙烯慢化体的中子,出射中子能量随着中子分离能呈现出规律的变化关系;随着γ能量增加,出射道开放增多,出射中子的能量总是分布在1 keV^4 MeV之间,探测器阵列在这一能区的平均效率为40%~46%。展开更多
Introduction Stroke is an important disease that is prevalent worldwide [1-3].Ischemic stroke accounts for 80%of stroke cases. Currently,evidence-based effective treatments for ischemic stroke are limited,and only int...Introduction Stroke is an important disease that is prevalent worldwide [1-3].Ischemic stroke accounts for 80%of stroke cases. Currently,evidence-based effective treatments for ischemic stroke are limited,and only intravenous throm- bolysis with Alteplase (a commercially available throm- bolytic agent)within 4.5 h of stroke onset and thrombectomy and arterial thrombolysis within 6-24h of onset are effective [4,5].However,because these two treatments have strict indications and certain risks (reper- fusion injury and bleeding)[5-8],there is an urgent need to develop new treatment methods.Thus,comprehensive elucidation of the molecular mechanisms underlying ischemic brain damage and the search for key signaling pathways and protein molecules are important for guiding the clinical treatment of ischemic stroke.展开更多
文摘平坦效率对于实现光中子反应的单中子、双中子和三中子事件的区分和截面的计算非常关键。介绍了一种用于逆康普顿散射γ源(Shanghai Laser Electron Gamma Source,SLEGS)光中子(γ,n)截面测量的4π平坦效率3He中子探测器阵列的设计与模拟。采用Geant4程序对平坦效率3He探测器的优化布局和效率进行了模拟,针对设计的由20只Φ50 mm×500 mm 5 cm 3He正比计数管和6只Φ25 mm×500 mm 3He正比计数管组成的4π平坦效率中子探测器,模拟给出探测器平均效率曲线在1 keV^6 MeV的效率为34.4%~45.9%。模拟中以209Bi靶为例,靶尺寸为Φ20 mm×4 mm,通过对产生中子的角分布,能谱的模拟计算,发现中子出射角度在90°对称,探测器的4π布局能够完全覆盖入射到聚乙烯慢化体的中子,出射中子能量随着中子分离能呈现出规律的变化关系;随着γ能量增加,出射道开放增多,出射中子的能量总是分布在1 keV^4 MeV之间,探测器阵列在这一能区的平均效率为40%~46%。
基金supported by the Natural Science Foundation of Guangdong Province, China (2017A030313869)the Science and Technology Project of Guangzhou City, China (201607010325)
文摘Introduction Stroke is an important disease that is prevalent worldwide [1-3].Ischemic stroke accounts for 80%of stroke cases. Currently,evidence-based effective treatments for ischemic stroke are limited,and only intravenous throm- bolysis with Alteplase (a commercially available throm- bolytic agent)within 4.5 h of stroke onset and thrombectomy and arterial thrombolysis within 6-24h of onset are effective [4,5].However,because these two treatments have strict indications and certain risks (reper- fusion injury and bleeding)[5-8],there is an urgent need to develop new treatment methods.Thus,comprehensive elucidation of the molecular mechanisms underlying ischemic brain damage and the search for key signaling pathways and protein molecules are important for guiding the clinical treatment of ischemic stroke.
